1. Field of the Invention
The present invention relates to bathing oils, and in particular, it relates to bathing oils which are readily dispersed within bath water.
2. Description of the Prior Art
In order to understand the requirements for an improved bathing oil, it is necessary to have some knowledge of the characteristics of the skin, especially its anatomy and physiology. Human skin is made up of layers and the outermost layer is itself composed of five different strata. The innermost stratum of the surface layer is the source of the cells for the others. Cells are constantly produced here by mitosis. One daughter cell remains in the stratum and the other pushes upward toward the surface, flattening and ultimately dying in a process called keratinization. These keratinized epithelial cells move through the outermost or keratin layer to the surface, where they are constantly shed and replaced.
Normal skin is almost waterproof because of the presence of a nongreasy, almost undetectable emollient film. Except for the palms of the hands and soles of the feet, skin contains sebaceous glands which secrete sebum, a complex mixture of fats, waxes and sterols which flows over the keratin layer, coating it with a thin, hydrophobic or waterproof film. After menopause, the secretion of sebum decreases so that dry skin is a very common problem for older women. Dry skin can also occur in younger individuals with normal skin as the result of exposure to wind or low humidity. In addition, the use of detergents, especially anionics, for skin cleansing can cause dry skin because they are such effective oil emulsifiers that they strip the skin of its natural oil.
Although dry skin, which is scaly and itchy, lacks water, soaking it in water, paradoxically, makes the condition worse. Because such skin is deficient in sebum, it absorbs water when immersed in water, swells, and becomes even more permeable to water. Upon removal from the water, water rapidly passes through the swollen skin leaving it drier than before.
Because of the natural, constant shedding and replacement of cells at the surface of the skin, there is no need to scrub the skin in order to cleanse it. In fact, it is harmful to do so because this layer is an important component of the protective barrier of the body. If this layer is removed by scrubbing or by accident, the whole process of skin growth is accelerated, but the time required for replacement is at least one day.
Although oils have been used in bathing since antiquity, they were not widely used in this country until relatively recently. In 1958, a group of dermatologists suggested bathing in an oil bath for the treatment of certain pathological skin conditions such as dry, chronic dermatosis. (Knox, John M., Everett, Mark Allen and Curtis, Arthur C., Arch. of Dermatology, 78, 642 (1958)). The bathing oil formulation consisted of a mixture of an alkylarylpolyether alcohol and an oil, either vegetable or mineral, which was to be added to a tubful of water in which the patient soaked for a short time. Knox et. al. reported that the "oil bath is an excellent therapeutic agent which is easily prepared and is effective in the treatment of selected dermatological conditions in which the skin is abnormally dry but not excessively inflamed."
Since then a variety of bathing oils have been produced and sold. The primary function of the early, popular bath oils was to perfume the bath and these products were sold as cosmetics, not drugs. According to Wells and Lubowe (Wells, F. V. and Lubowe, Irwin I., Cosmetics and the Skin, Reinhold Publishing Co., N.Y., 1964, p. 333), a "true bath oil is virtually water insoluble and when poured into the bath should form a perfumed oily film that spreads over the surface of the water producing a maximum diffusion of fragrance. Any oil left on the body should feel pleasantly emollient, neither greasy nor sticky and then the inevitable bath tub `ring` should be easily removable."
These bath oils, now called "floating bath oils" contained large amounts, up to 75% by weight, of perfume. The remaining ingredients are an oil, either vegetable or mineral, a small amount of a fatty alcohol to promote spreading and a small amount of a surfactant to aid in cleaning the tub.
The Schmolka U.S. Pat. No. 3,624,208 issued on Nov. 30, 1971 describes one such "floating bath oil" composition. The Schmolka Patent states that bath oils may be classified as "spreading bath oils; dispersible bath oils; highly perfumed bath oils; soluble bath oils; foaming bath oils; and germacidal bath oils. The first three can be considered true bath oils, while the latter three are aqueous preparations containing solubilized oil." The Schmolka Patent states that a bath oil should be a sparkling clear solution, and that, when poured into a tub of water, should spread rapidly and evenly on the surface of the warm water. The Schmolka Patent describes an improved spreading bath oil which does not form unattractive blobs on the surface of the bath water, which is not greasy on the skin and which does not leave an oily scum on the emptied tub.
However, such bath oils have not been entirely satisfactory. Robert L. Goldenberg points out (Goldenberg, Robert L., Cosmetics and Toiletries, 94, #7, 55 (1979)), that floating bath oils have "the disadvantages that the amount of oil deposited is often not uniform as the bather arises from the tub and that a calcium scum produced by the use of soap as a cleansing agent causes problems."